Getting list of pixel values from PIL

Question

Guys, I\'m looking for a bit of assistance. I\'m a newbie programmer and one of the problems I\'m having at the minute is trying to convert a black & white .jpg

Answer 1

Or if you want to count white or black pixels

This is also a solution:

from PIL import Image
import operator

img = Image.open("your_file.png").convert('1')
black, white = img.getcolors()

print black[0]
print white[0]

Answer 2

Looks like PILlow may have changed tostring() to tobytes(). When trying to extract RGBA pixels to get them into an OpenGL texture, the following worked for me (within the glTexImage2D call which I omit for brevity).

from PIL import Image
img = Image.open("mandrill.png").rotate(180).transpose(Image.FLIP_LEFT_RIGHT)

# use img.convert("RGBA").tobytes() as texels

Answer 3

As I commented above, problem seems to be the conversion from PIL internal list format to a standard python list type. I've found that Image.tostring() is much faster, and depending on your needs it might be enough. In my case, I needed to calculate the CRC32 digest of image data, and it suited fine.

If you need to perform more complex calculations, tom10 response involving numpy might be what you need.